The example you have mentioned only uses Python in the backend. It's based on Django or Flask. Then, in the frontend, it uses JavaScript.
Building a SaaS from scratch required a lot of time. Happy to see a 100% Python SaaS Starter kit, usually it was reserved for JavaScript because of the frontend. In the past, you are forced to use JavaScript for the frontend.
I know it because I'm the author of Nextless.js [1], a full-stack JavaScript starter kit that is totally based on JavasScript, from frontend to backend. Using only one programming language was my competitive advantage compared to the boilerplate based on Ruby, Python or PHP.
I think in the future more and more languages can be used in the frontend like Rust, etc... There are already some frameworks you can use to build frontend in Rust. It's only the beginning.
PySaaS uses the Pynecone web framework rather than Django or Flask.
This allows you to build the entire stack in a single language instead of having to learn and switch between multiple. You can install and import any Python library as you would with any Python file.
The frontend is compiled down to a NextJS app, and FastAPI is built-in for the backend. UI components are fully-customizable, and are actually wrappers around React components using Chakra UI.
That kind of other-language-to-JS stuff works great for small, one-man projects that never go to production. Unfortunately, other than TypeScript, none of these solutions have really achieved critical mass, and they all fizzle out after a few years, leaving you with a horrible mess to clean up. You have layers and layers of indirection, and you don't know whether your problem is your code, or a Python library, or the Python-to-JS layer, or one of the JS libraries, and no one on the Internet can help you because your stack is completely bespoke.
I applaud you trying to make it easier for people to get started, but throwing them on top of this Tower of Babel and pretending it will never come crumbling down into a mess of inconsistent languages and libraries is a recipe for pain. TypeScript is not that hard. If you're teaching beginners how to build a web front end, just start with that, and let them use either TypeScript or Python on the back end, depending on how ambitious they are.
Django (Python)
Flask (Python) https://github.com/smirnov-am/awesome-saas-boilerplates